The purpose of this project is to elucidate the neural mechanisms and principles of treatment of chronic pain syndromes. We are conducting clinical trials of single drugs, drug combinations, and alternative medicine techniques in chronic lumbar radiculopathy pain. A new program in pain genetics has localized a gene affecting pain behaviors to a small region of one chromosome containing several genes whose gene products have previously been linked to pain processing. Candidate gene studies are beginning in a cohort of 500 patients with 10-year followup of sciatica in the Maine Lumbar Spine Study, and with cohorts of patients with other neuropathic pain disorders and temporomandibular disorder.